World Water Day - March 22:

Freshwater - a dwindling resource

The world’s population has surpassed seven billion! What does this mean in terms of meeting basic needs such as water and food? A growing demand that cannot keep pace with available resources, especially when it comes to water. Even though the supply of food can be increased the water resources cannot be increased as it is not a growing natural resource .It is in fact a fast dwindling resource that can pose a serious threat to the survival of not only all living beings but also the plant kingdom . Freshwater is a scarce resource; its annual availability is limited and the demand is growing. Freshwater is an important natural resource necessary for the survival of all ecosystems. So, in general if there is no water there cannot be any life :water is a critical issue for the survival of all living organisms.

Some organisms can use salt water but many including the great majority of higher plants and most mammals must have access to freshwater to live.

Today there are more people relying on a finite amount of freshwater for their survival than in the past . With World Water Day just round the corner we like to focus on some vital information on this wonder liquid many of us waste without understanding the consequences of our careless actions.

The world is heading towards a water crisis. Scientists say that if global warming continues to melt glaciers in the polar regions, as expected, the supply of freshwater may actually decrease; First, freshwater from the melting glaciers will mingle with salt water in the oceans and become too salty to drink. Second, the increased ocean volume will cause sea levels to rise,contaminating freshwater sources along coastal regions with seawater.

Freshwater is a renewable and changeable, but limited natural resource. Freshwater can only be renewed through the process of the water cycle, where water from seas, lakes, rivers, and dams evaporates, forms clouds, and returns to water sources as precipitation. However, if more freshwater is consumed through human activities than is restored by nature, the result is that the quantity of freshwater available in lakes, rivers, dams and underground waters is reduced which can cause serious damage to the surrounding environment.In order to better understand water use and availability trends, scientists divide the Earth’s surface into river basins. In each basin, the primary source of water is precipitation. Rain and snow feed the river and its tributaries, as well as groundwater, ponds, and lakes. Precipitation also adds moisture to the soil, and crops take up the moisture through their roots.

What is freshwater?

Freshwater is naturally occurring water on the Earth’s surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Freshwater is generally characterised by having low concentrations of dissolved salts and other total dissolved solids. Freshwater is defined as having a low salt concentration — usually less than 1 per cent .Plants and animals in freshwater regions are adjusted to the low salt content and would not be able to survive in areas of high salt concentration (i.e. ocean).The term specifically excludes seawater and brackish water although it does include mineral rich waters such as chalybeate springs. The term “sweet water” has been used to describe freshwater in contrast to salt water.

Sources of freshwater

The source of almost all freshwater is precipitation from the atmosphere, in the form of mist, rain and snow. Precipitation also adds moisture to the soil.

Most crops around the world are grown using only the soil moisture provided by rainfall. When this moisture is insufficient, farmers apply more water through irrigation. Some rain or irrigation water evaporates without benefiting the plant, while some transpires through the plant’s tissues during photosynthesis and returns to the atmosphere. Water transformed into vapour in either of these ways is not available for use again in that local area, so in practical terms, it is lost or “consumed.”

Freshwater falling as mist, rain or snow contains materials dissolved from the atmosphere and material from the sea and land over which the rain bearing clouds have travelled.

In industrialized areas rain is typically acidic because of dissolved oxides of sulfur and nitrogen formed from burning of fossil fuels in cars, factories, trains and aircraft and from the atmospheric emissions of industry. In extreme cases this acid rain results in pollution of lakes and rivers in parts of Scandinavia, Scotland, Wales and the United States.

In coastal areas freshwater may contain significant concentrations of salts derived from the sea if windy conditions have lifted drops of seawater into the rain-bearing clouds. This can give rise to elevated concentrations of sodium, chloride, magnesium and sulfate as well as many other compounds in smaller concentrations.

In desert areas, or areas with impoverished or dusty soils, rain-bearing winds can pick up sand and dust and this can be deposited elsewhere in precipitation and causing the freshwater flow to be measurably contaminated both by insoluble solids but also by the soluble components of those soils. Significant quantities of iron may be transported in this way including the well-documented transfer of iron-rich rainfall falling in Brazil derived from sand-storms in the Sahara in north Africa.

Water distribution

Do you know that out of all the water on the Earth, only 2.75 per cent is freshwater? But even that is limited because it includes 2.05 per cent of water which is frozen in glaciers, 0.68 per cent as groundwater and 0.011 per cent as surface water in lakes and rivers. Freshwater lakes, most notably Lake Baikal in Russia and the Great Lakes in North America, contain seven-eighths of this fresh surface water. Swamps have most of the balance with only a small amount in rivers.

The atmosphere contains 0.04 per cent water. In areas with no freshwater on the ground surface, fresh water derived from precipitation may, because of its lower density, overlie saline ground water in lenses or layers.Most of the world’s fresh water is frozen in ice sheets. Many areas suffer from lack of distribution of freshwater, such as deserts and uncommonly known; Florida, US.

Causes of limited freshwater

There are many causes of the apparent decrease in our freshwater supply. Principle amongst these is the increase in population through increasing life expectancy, the increase in per capita water use and the desire of many people to live in warm climates that have naturally low levels of freshwater resources.

Climate change is also likely to alter the availability and distribution of fresh water across the planet.

[Fast facts]

* Freshwater can be defined as water with less than 500 parts per million (ppm) of dissolved salts ( This may differ from one source to another)

* Scientifically, freshwater habitats are divided into lentic systems, which are the stillwaters including ponds, lakes, swamps and mires

* Agriculture is the human activity that consumes the most fresh water.

* Changes in landscape by the removal of trees and soils change the flow of freshwater in the local environment and also affect the cycle of freshwater.

* Pollution from human activity, including oil spills, also presents a problem for freshwater resources.

* Fresh and unpolluted water accounts for 0.003 per cent of total water available globally.

* Some terrestrial mammals, especially desert rodents appear to survive without drinking but they do generate water through the metabolism of cereal seeds and they also have mechanisms to conserve water to the maximum degree.

* The use of water by humans for activities such as irrigation and industrial applications can have adverse impacts on down-stream ecosystems.

* Chemical contamination of fresh water can also seriously damage eco-systems.

* Water used by the agricultural sector accounts for nearly 92 per cent of annual global freshwater consumption, according to a recent study.